I have read about this problem over and over again - it happened to me as well. My setup was:

J!1.12
CB 1.1
SMF 1.1.2
JSMF 2.0

Everything was fine until suddenly any topic that had more than 1 page was not showing up (people have experienced funny other issues too). I went around hunting for solutions but nothing helped. It seems as it is an issues with the php 5.2.5 upgrade - almost everybody who has experienced this is because of the upgrade.

My 1st instinct was to take the time to upgrade J!1.15, and SMF to 1.1.4 and use the new JSMF 2.0.21a bridge - that didn't help.

Solution 1: (didn't work for me because not all shared hosts allow this)